Sequential drawer slide

ABSTRACT

A sequential drawer slide is disclosed having rails that extend in a predetermined order, resulting in the weight of the drawer initially carried by multiple slides concurrently to increase the load rating of the assembly and prolong the life cycle of the drawer slide. The sequential actuation of the slide rails as the drawer is withdrawn from the cabinet is achieved by incorporating a catch between the small slide rail and the intermediate slide rail that resists extension of the small slide rail from the intermediate slide rail up to a decoupling force. If the decoupling force is greater than the force required to extend the intermediate slide rail from the large slide rail, then the intermediate slide rail and small slide rail nested therein will extend first, and the small slide rail with extend from the intermediate slide rail only after the intermediate slide rail is fully extended.

FIELD OF THE INVENTION

The invention relates generally to drawer slides, and more particularly to a drawer slide with a sequential opening mechanism.

BACKGROUND OF THE INVENTION

The use of drawer slides for file cabinets are well known. The drawer slides support the shelves or drawers in the cabinet, and extend horizontally to allow the shelves to be accessed external to the cabinet, facilitating both the retrieval and return of documents stored therein.

A typical drawer slide has a plurality of nested or stacked rails that may slide against a set of bearings, especially ball bearings. The bearings are located in raceways longitudinally disposed along the slide rails. In a typical horizontal slide configuration, a first large slide rail is mounted to each inner side wall of the cabinet at the designated location for the shelf. A second, smaller slide rail is rigidly affixed to the drawer such that the drawer extends horizontally and is supported outside the cabinet by the smaller slide rail. Each slide rail includes a longitudinal track that runs parallel to the bearing raceway substantially along the length of the rail. In a three-slide configuration, an intermediate rail cooperates with the cabinet slide rail and the drawer slide rail to further extend the drawer. Although less common, additional slide members can be added to the embodiment just described.

The arrangement of the slide rails can take various forms, such as a vertical stacking of the slide rails or, more commonly, a nesting of the slide rails in a telescoping arrangement. With a telescoping slide arrangement, there is typically a small slide rail (the “inner rail”) connected to the drawer that fits into the intermediate slide rail, which in turn fits into the large slide rail (the “outer rail”) affixed to the cabinet. These three rails telescope in a known manner to extend the file drawer outward from the cabinet. When the drawer is withdrawn from the cabinet, a user applies a horizontal force to a handle on the face of the drawer causing the drawer to extend outward from the cabinet in a cantilever arrangement as the slide rails expand horizontally. Because the smallest slide rail is connected to the drawer itself, when the horizontal force is applied to the drawer the small slide rail translates horizontally with respect to the intermediate slide, causing the drawer to be supported substantially by the small slide rail. During this initial movement of the drawer the intermediate slide rail remains stationary within the larger slide rail. When the small slide rail becomes fully extended within the intermediate slide rail, usually defined by a stop on the intermediate rail, the intermediate slide rail begins to translate horizontally within the large slide. If there is only one intermediate slide, then the drawer has reached its maximum horizontal displacement from the cabinet when the intermediate slide rail is fully extended from the large slide rail.

One shortcoming of the above-described slide arrangement is that the smallest slide supports the entire file cabinet for the initial movement of the drawer translation. Only after the small slide is fully extended does the intermediate slide begin to extend and support some of the load. Because often times the drawer need only be partially withdrawn to retrieve a file or return a document, the small slide will be subjected to a disproportionately high percentage of total time supporting the shelve while the shelve is extended from the cabinet. Placing the entire load on the smallest slide has the effect of shortening the life cycle of the slides and limited the load rating of the drawer itself. Premature failure or wear of the slides results, necessitating replacement of the slides and can lead to the entire cabinet being scrapped at considerable cost to the user. What is needed in the art is a system that prolongs the life cycle and increases the load rating of a multi-slide arrangement.

SUMMARY OF THE INVENTION

The present invention provides a sequential extraction of the drawer slide rails that results in the weight of the drawer initially carried by both the combination of the intermediate and small slide rails concurrently, thereby increasing the load rating of the assembly and prolonging the life cycle of the drawer slides. The sequential actuation of the slide rails as the drawer is withdrawn from the cabinet is achieved by incorporating a catch or other impediment between the small slide rail and the intermediate slide rail that resists extension of the small slide rail from the intermediate slide rail up to a separation force J. As long as force J is greater than the force required to extend the intermediate slide rail from the large slide rail, then the intermediate slide rail (and small slide rail nested therein) will extend first, and the small slide rail with extend from the intermediate slide rail only after the intermediate slide rail is fully extended. The catch between the small and intermediate rails can be achieved by an interfering contact between the small and intermediate slides where the frictional forces of the contact resists separation of the two slide rails up to a separation force J_(friction). Alternate catches may be based on the deflection of an interfering member or other force generating mechanisms in additional to the frictional force achieved by the embodiment discussed below.

In a first embodiment, the impediment may be a V-shaped notch formed in the channel of the small slide rail that interferes with a detent block on the intermediate slide rail, resisting extension of the small slide rail within the intermediate slide rail. The frictional force needed to overcome the interference of the V-shaped notch against the detent block need not be large, rather it simply needs to be of sufficient magnitude that the intermediate slide rail extends before extension of the small slide rail. When the drawer is returned to the cabinet, the small slide first retracts into the intermediate slide again following the sequential expansion in reverse, once again ensuring that the shelf is supported by the combination of the intermediate and small slide rails for one half of the travel of the drawer. The insertion of the drawer into the cabinet forces the V-shaped notch or other protrusion over and past the detent or other frictional member resetting the mechanism for the next sequential extraction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is front view, partially in shadow, of an embodiment of the multiple rail slide of the present invention;

FIG. 2 is an elevated perspective view of the small rail of the embodiment of FIG. 1;

FIG. 3 is an elevated perspective view of a portion of the small rail of the embodiment of FIG. 1 engaging the detent of the intermediate rail;

FIG. 4 a is a front view of the detent mechanism of FIG. 3;

FIG. 4 b is a side view of the detent mechanism of FIG. 3;

FIG. 4 c is an elevated, perspective view of the detent mechanism of FIG. 3;

FIG. 5 is a magnified view of encircled portion of FIG. 1;

FIG. 6 is a front view, partially in shadow, of the embodiment of FIG. 1 with the intermediate slide rail extended from the outer slide rail; and

FIG. 7 is a front view, partially in shadow, of the embodiment of FIG. 1 with the slide fully extended.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a three piece telescoping slide 10 comprising three rails, an outer rail 20, an intermediate rail 25, and an inner rail 30. The slide is used to support a file shelf or drawer in a file cabinet, and extend the drawer horizontally outward from the cabinet to access files, documents, and the like. The respective rails telescope from within each other in a well known manner to support the drawer outside of the cabinet. A cabinet will typically include three or more such drawers, with slides on each side supporting each drawer. That is, each drawer will typically have a left slide and a right slide mounting the drawer to the inside walls of the cabinet. While this disclosure may refer to the slide as singular in some references, it is to be understood that the slides are usually used in pairs to provide the support for each drawer.

The innermost rail 30 slides longitudinally within the intermediate rail 25, which in turn slides longitudinally within the outermost rail 20. The inner rail 30, as shown in FIG. 2, has a planar front panel 35 extending longitudinally with upper traverse edge 40 and lower traverse edge 45 extending perpendicular thereto forming a substantially “C” shaped beam. On the outer surface 55 of each traverse edge 40,45 of the inner rail 30 is a concave recess 50 extending substantially the longitudinal length of the inner rail 30. Each concave recess 50 forms half of a ball bearing raceway that cooperates with a complimentary concave recess on the inner surface 60 of traverse upper and lower edges 65, 70 of the intermediate rail 25 as shown in FIG. 7. The front panel 35 includes a plurality of apertures 75 for use with a bracket (not shown) to secure the slide 10 to a retractable drawer, where fasteners (not shown) pass through the apertures 75 and corresponding holes in the bracket and drawer in a known manner. At a distal end 72 of the inner rail 30 is a flap 80 that cooperates with a detent 100 on the intermediate rail 25 to define the closed or withdrawn position. That is, when the slide 10 is retracting from its telescoped or extended position the inner rail 30 stops translation with respect to the intermediate rail 25 when the flap 80 contacts with the arcuate bumper 85 of the detent 100 of the intermediate rail 25. The arcuate bumper 85 has some resiliency to absorb some of the energy of the moving drawer so that the drawer does not bounce off the intermediate rail 25 with substantial force.

Spaced a short distance from the distal end 72 of the inner rail 30 is a “V” shaped notch 95 projecting inwardly from the upper traverse edge 40 at an inner surface 54 (see FIG. 5). The “V” shaped notch is adjacent and proximal to the longitudinal position of the detent 100 of the intermediate rail 25 when the slide is contracted so that the end flap 80 and “V” shaped notch 95 border the detent 100. The “V” shaped notch 95 has a vertical dimension such that the apex 97 extends into a path defined by the movement of a bypass surface 105 of the detent 100 as the intermediate rail 25 moves with respect to the inner rail 30. In other words, the movement of the inner rail 30 with respect to the intermediate rail 25 causes the V-shaped notch 95 to come in contact with the bypass surface 105 of the detent 100 on the intermediate rail 25. The frictional interference of the “V” shaped notch 95 with the by pass surface 105 of the detent 100 can be overcome by a supplemental horizontal force J corresponding to the frictional force resisting the movement of the “V” shaped notch across the surface of the bypass surface (see FIG. 3). After the “V” shaped notch of the inner rail travels across the bypass surface 105, the supplemental force J is eliminated and the inner rail 30 will move freely within the intermediate rail 25.

The detent 100 of the intermediate rail 25 is shown in FIG. 4 a-c. The energy absorbing arcuate bumper 85 extends from a substantially planar base 110. Extending from the base 110 are outwardly directed fingers 115 defining channels 120 for receiving the respective traverse edges 40,45 of the inner rail 30. Thus, when the inner rail 30 is in proximity with and parallel to the intermediate rail 25, the upper edge 40 and lower edge 45 of the inner rail 30 are disposed in the channels 120 defined by fingers 115 a,b. The detent 100 further includes angled tabs 130 that locate the detent 100 on the intermediate rail 25 by cooperating with mating slots 145 on the intermediate rail.

Disposed on the detent 100 along on upper portion of the base 110 is a substantially rectangular stop 150 that supplies the bypass surface 105 for the sequential opening of the rails. The stop 150 includes a preliminary contact surface 155 defined by a proximal end surface that is adjacent to the V shaped notch 95 (FIG. 5) when the slide is fully retracted. When a force is applied to the drawer to withdraw the drawer from the cabinet, the horizontal force applied to the drawer is transferred to the small rail(s) 30 to which it is attached. Unlike the prior art slides that would allow the inner rail to fully extend before translation of the intermediate rail would initiate, in the present invention the initial movement of the inner slide 30 causes the V-shaped notch 95 to bear against the contact surface 155 of the stop 150 on the detent 100 of the intermediate rail 25. By orienting the bypass surface 105 parallel to the direction of travel of the inner rail, a predictable force to overcome the friction between the V-shaped notch and the bypass surface is established. The force required to overcome the interference of the V shaped notch 95 with the stop 150 (i.e., the initial deflection of the stop plus the friction resisting the movement of the notch dragging across the bypass surface 105 of the stop, referred herein as force J) is greater than the ordinary force required to move the intermediate rail 25 within the outer rail 20. Accordingly, the horizontal force applied to the drawer is transferred through the inner rail 30, across the sequential release mechanism, to the intermediate rail 25, causing it to slide within the fixed outer rail 20.

As the intermediate rail 25 extends in a cantilevered manner away from the outer rail 20, the weight of the shelf is supported by the combination of the inner rail 30 and the intermediate rail 25. The structural capacity of this combination is significantly greater than the weight bearing capacity of the inner rail alone. For a standard one hundred pound rated full extension slide, the sequential extension of the intermediate and inner rails can increase the load capacity to approximately one hundred forty to one hundred fifty pounds, resulting in a fifty percent increase in load capability. This also has a significant impact on the life cycle of the slide 10, and particularly the wear of the inner slide rail 30 which no longer bears the full weight of the drawer during the initial stages of extraction. This increase in life cycle and load capacity is a function of the sequential slide actuation and is not found in the prior art.

Once the intermediate rail 25 is fully extended (FIG. 6), an additional force J is necessary to further move the drawer away from the file cabinet. The force J is defined as the amount of force required to overcome the sequential actuator—in this case the force required to overcome the interference of the V-shaped notch 95 with the contact surface 105 of the stop 150. When this incremental force J is applied, the further extraction of the drawer is achieved as the V-shaped notch passes across the contact surface, after which only the normal extracting force is required to fully open the drawer (FIG. 7). The fully extended position is set by the engagement of a wedge shaped detent (not shown) on the front panel 35 of the inner rail at a proximal end 74 that engages the beveled edge 175 of the detent 100 to arrest further extension of the inner rail 30 from the intermediate rail 25.

The rails are preferably made of a metal such as steel to support the loads of the cantilevered shelves. The detent 100 is preferably formed of a hard polymer or plastic with some give, such that the interference with the V-shaped notch will cause the detent to yield and permit passage when the required force J is applied.

The sequential opening of the slide 10 is shown in FIGS. 1, 6 and 7. Initially fully retracted, the inner rail 30 is seated within the intermediate rail 25, which in turn is seated within outer rail 20. Applying an outward horizontal force to the drawer initially will tend to cause the attached inner rail 30 with move within the intermediate rail 25. However, the movement of the inner rail 30 is arrested by the interference of the V-shaped notch 95 with the stop 150 on the detent 100 of the intermediate rail 25. As a result, as shown in FIG. 6 the inner rail 30 and intermediate rail 25 initially extend together from within the outer rail 20. Thus, up to and including the extended position of the slide 10 as shown in FIG. 6, the drawer is supported by the combination of the inner rail 30 and the intermediate rail 25. Further applied force J will cause the V-shaped notch to deflect the detent 100 slightly cause the notch to drag across the bypass surface 105 until it separates from the detent 100. This permits the inner rail to then extend unhindered from the intermediate rail until the slide is fully extended as shown in FIG. 7. When the drawer is returned to the cabinet, the V-shaped notch of the inner rail is forced back across the bypass surface 105 of the detent to reset the mechanism for the next use.

While the above described embodiments disclose a frictional engagement of the detent with a protrusion of the cooperating rail, it may be appreciated that the invention is not limited to the above described embodiments for one of ordinary skill in the art would recognize that the sequential slide can be achieved by various mechanisms. For example, the force J required to overcome the movement of the inner slide rail within the intermediate slide rail can be prescribed by the deflection of one member on the inner rail interfering with a member of the intermediate rail during relative translation. Alternatively, the frictional force can be developed in various ways besides that disclosed, and is not limited to a V-shaped notch with a flat surface. The release of the inner rail from the intermediate rail could also require a manual actuation, such as depressing a button to eliminate an interfering member. Therefore, it is to be understood that the invention is not limited to those embodiments described above, but rather is includes all scope as defined by the claims appended hereto. 

1. A multi-rail drawer slide with sequential extension comprising: a first slide rail; a second slide rail moveable along said first slide rail; a third slide moveable along said second slide; and an interference between said second slide rail and said third slide rail, coupling said second and third slide rails together, said interference establishing a decoupling force and wherein the force required to move said second slide rail along said first slide rail is less than the force required to decouple said second slide rail and said third slide rail.
 2. The multi-rail drawer slide of claim 1 wherein said interference comprises a projection on said third slide rail that interferes with a path of the second slide rail when said third slide rail moves along said second slide rail.
 3. The multi-rail drawer slide of claim 2 wherein said projection on said third slide rail comprises a V-shaped notch formed on a surface thereof.
 4. The multi-rail drawer slide of claim 1 wherein said second slide rail includes a detent at a first end, said detent disposed to resist movement of the third slide rail along said second slide rail.
 5. The multi-rail drawer slide of claim 4 wherein said detent includes a stop having a flat surface oriented parallel to the travel of the third slide rail, and said third slide rail has a projection that frictionally engages said flat surface of the detent to couple said second and third slide rails together.
 6. The multi-rail drawer slide of claim 5 wherein said projection on said third slide rail comprises a V-shaped notch that cooperates with said flat surface on said detent to frictionally couple said second and third slide rails.
 7. The multi-rail drawer slide of claim 1 wherein said second slide rail extends telescopically from within said first slide rail, and said third slide rail extends telescopically from within said second slide rail.
 8. A multi-rail drawer slide with sequential extension having outer, intermediate, and inner rails, comprising: means for sliding said intermediate rail within said outer rail; means for sliding said inner rail within said intermediate rail; and means for sequentially sliding said intermediate rail within said outer rail before sliding said inner rail within said intermediate rail.
 9. A multi-rail drawer slide with sequential extension of rails comprising: an outer rail; an inner rail including a V-shaped notch projecting inwardly from a traverse edge; and an intermediate rail including a detent at a first end cooperating with said V-shaped notch of said inner rail to couple said inner rail to said intermediate rail, and wherein said inner rail is disengaged from said intermediate rail upon an extension of the intermediate rail from within said outer rail. 